Born in Cambridge, Massachusetts, Marcia Sheldon Moore was the daughter of Robert L. Moore, who founded the Sheraton Hotel chain. Over the course of her life she married four times. With her first husband and their three children, she spent time India studying Hinduism. With her third husband, Mark Douglas, she co-authored several New Age books. Along with lecturing to promote her books, Moore worked as a yoga teacher and astrological counselor. She eventually developed her own approach to reincarnation therapy, which she called "hypersentience". She promoted this therapy through the Ananta Foundation in Ojai, California, and via the quarterly Hypersentience Bulletin that she began publishing in 1975.
Moore's initial ketamine experience took place in April of 1976. About a year later, she met the man who became her fourth husband, an anesthesiologist named Howard "Sunny" Alltounian. Together they wrote the book Journeys into the Bright World, which chronicled their experimentations with ketamine. Moore coined the term "samadhi therapy" for the new blissful drug-induced self-exploration that she and Alltounian began working with and providing to others. Less than three years after her first ketamine experience--and following her increasing and problematic use of the drug, which she ended up hiding from Alltounian--Moore passed away in what was likely the first known behavioral fatality associated with ketamine. However, there are some conflicting accounts related to her disappearance and death; Alltounian and at least one of her children have stated that they believe Moore committed suicide.

Note: Within a chapter of this "true crime" book titled "The Lost Lady", which presents the story surrounding Marcia Moore's disappearance and death, Howard "Sunny" Alltounian is first referred to by the name Steve Monti, and later by the name Walter "Happy" Boccaci, which author Ann Rule says Monti had chosen as his new name. The story is again repeated in the 2003 collection Without Pity: Ann Rule's Most Dangerous Killers.